This invention relates to a combination tool for use in oil well drilling and production. The tool performs both cutting and retrieving functions within a well bore.
Prior tubing cutters of various types are known, including exposive devices and tools having cutter knives operated by hydraulic pistons to which fluid pressure is directed from the surface. Hydraulic cutters tend to be complex, and therefore expensive and difficult to operate, and explosive devices have well-known shortcomings and dangers Furthermore, none of the prior devices is capable of both cutting a fish and retrieving it from the well in a single operation.
Purely mechanical tubing cutters are also well known. These, as a rule, require that the tubing supporting the tool be rotated at the surface when it is desired to perform a cut. A problem associated with tools actuated by rotary motion occurs when well bores are highly deviated, that is, not straight. Such bores may deviate from the vertical by over 60.degree. . In such cases, wall friction between the casing and the tubing makes rotary motion very difficult to impart and control from the surface.